Fuse link



C. A. FOX

FUSE LINK Dec. 8, 1942.

Filed Sept. 16, 1940 //Y VE/YTOE, (Imeusfipw Fox 711f.

ArTOE/YEY Patented Dec. 8, 1942 Charles AdinFox, St. Louis, Mo.,asaignor James B. Kearney Corporation. St. Louis, Mo.,

a eorporation of Missouri. Application September 16, 1940, Serial No.356,932

3 Claims.

This invention relates generally to fuse links adapted for use inassociation with electrical switches, and more specifically to fuselinks intended for use with fuse switches of the type disclosed inUnited States Letters Patent No. 2,086,028, issued July 6, 1937, thepredominant object of the invention being to provide a fuse link which.is of such improved construction and arrangement that the operation ofapplying the fuse link to a switch of the type covered by" the patentidentified above is rendered much more convenient than was the case whenfuse links of the type heretofore used with these switches wereemployed.

In applying a-fuse link to a switch of the type disclosed in theabove-identified patent the finger of a switch stick is introduced intoan eye at the upper end ofthe fuse link, there being one of such eyes ateach end of the fuse link, and the lower portion of the fuse link isdrawn into engagement with the link-engaging portion of the lower,resilient contact of the switch. The switch stick is then elevated tomove the fuse link upwardly and thereby draw the outer portion of thelower, resilient contact of the switch the fuse link could be applied tothe upper contact of the.switch.

In order to eliminate the likelihood of the upv per eye of the fuse linksliding of! of the finger of the switch stick as described above, theimproved fuse link disclosed herein was devised. The improved fuse linkis provided with eyes at its opposite ends at least one of which isshaped to provide an inner eye portion of substantially circular shapeand an outer eye portion of reduced width. In applying one of theseimproved fuse links to a switch the finger of the switch head at theouter end of said finger will effectively prevent the eye of the fuselink from sliding of! of the switch stick finger.

upwardly against the tendency of said outer portion of said lower,resilient contact of the switch to move downwardly because of theresilient nature of said lower contact. When the fuse link has beenelevated the required distance the upper portion thereof is drawn intoengagement with the fuse link-engaging portion of the upper contact ofthe switchand the finger of the switch stick is removed from the uppereye of the fuse link, whereupon the fuse link will be held under tensionbetween the upper and lower contacts of the switch. 0n occurrence of afault on the line with which the switch is associated, ,which is of acharacter to rupture the fuse link, the outer portion of the lower,resilient contact is released and snaps downwardly to separate therupturedends of the fuse link.

Fuse links employed heretofore with switches of the type described abovehave included each a pair of eyes which were of substantially circularshape. As a result of this situation it sometimes happened that inapplying one of these earlier fuse links" to a switch of the typedescribed above, the downward pull exerted on the fuse link by thelower, resilient contact of the switch when the fuse link was beingelevated to engage its upper portion with the upper contact of theswitch, caused the upper eye of the fuse link to unintentionally slideon of the finger of the switch stick before the upper portion of Fig. lis a perspectivev view illustrating the manner in which one of theimproved fuse links disclosed herein isapplied to a switch with the aidof a switch stick.

Fig. 2 is an enlarged fragmentary sectional elevation illustrating theimproved fuse link.

Fig. 3 is an enlarged side elevation of one of the eyes of the fuse linkand parts located ad-- iacent thereto.

Fig. 4 is a front elevation of the structure 0 Fig. 3 but showing insection the button associated with fuse link eye.

Fig. 5 is an enlarged horizontal section taken on line 5-5 of Fig. 4.

In the drawing, wherein is shown for the purpose of illustration,merely, one embodiment of the invention, A designates generally a switchof the type with which the improved fuse link disclosed herein isadapted for association. Briefly stated the switch A comprises amounting in the form of an insulator B which has mounted thereon at itstop and bottom an upper terminal C and a lower terminal D, respectively,portions E of the electrical circuit with which the switch is associatedbeing mechanically and electrically connected "to said upper and lowerterminals by suitable connecting means F. Se-

cured mechanically and connected electrically to the upper terminal C isan upper contact G, and

likewise secured mechanically and connected electrically to the lowerterminal I) is a lower contact H. The upper and lower contacts of theparticular switch illustrated in the drawing are formed of relativelyheavy wire shaped to the desired configuration, the upper contact beingrelatively rigid and the lower contact being resilient and having coiledportions H to give the desired resiliency thereto. Also the upper andlower contacts G and H are provided with rearwardly bent portions J atopposite sides of each thereof which cooperate with portions of thecontacts located inwardly of said rearwardly bent portions to providefuse link-engaging portions.

The improved fuse link of the present invention is designated generallyin the drawing by the reference character L and said fuse link includesa pair of terminal conductors i and 2 which are connected together attheir inner ends in a manner to provide the fuse link with a fusiblesection. The fuse link L may be provided with a fusible section invarious ways inasmuch as the precise construction of the fuse link inthis regard is not important to the present invention. However in theinterest of completeness of disclosure it is pointed out that the inner,adjacent end portions of the terminal conductors i and 2 may haveclamped, or otherwise secured thereto, a pair of members I which arespaced apart longitudinally of the link. The members I are connectedtogether by a strain wire I which imparts to the fusible section of thelink the strength required to resist tensional strains to which the fuselink is subjected, and a fusible element 5 is attached mechanically andconnected electrically to the members 3 and is turned about the strainwire 4.

The fusible section of the fuse link L is surrounded by a tube structurewhich preferably, though not necessarily, comprises an inner tube 6formed of horn fiber, or similar material, which is characterized by theability to give of! gas in the presence of an electrical are whichtendsto extinguish the arc, and an outer tube formed of Bakelite, orother suitable material, which provides the tube structure with therequired strength against bursting and gives to said tube structure thenecessary weather protection. At one of its ends the tube structureabuts against a disk I which is soldered, or otherwise secured, to theconductor I, and at the opposite end of said tube structure a similardisk 8, which is unattached to the conductor 2, is forced against saidend of said tube structure by a coil spring 9 which is interposed undercompression between said disk 8 and an abutment 8' which is soldered orotherwise secured to the conductor 2.

Secured to the conductor I of the fuse link L. at the outer end thereof,is an eye I! which is formed of substantially rigid material, such, for

instance, as substantially stiff wire. The eye IO includes an innerportion IOa of substantially circular shape from which is extended apair of substantially parallel legs Iflb, and extended from said inner,circular portion IIIa at the end opposite to the end at which the legsIIlb are located is an extension IIIc of reduced width. The legs, innercircular portion, and extension of the eye II! are formed from a singlelength of material, the extension being comprised of opposed, parallelside portions which are joined by a curved bridge portion as shown tothe best advantage in Figs. 2 and 4. The eye I 0 is secured to the endportion of the conductor I by a clamping element II, said clampingeiernent including a flange portion Na and a tubular portion III) ofelongated shape. The end portion of the conductor I is extended upwardlyinto the tubular portion of the clamping element II and the legs lb ofthe eye I0 are extended downwardly into said tubular portion of saidclamping element, as shown in Fig. 4, and clamping pressure is appliedto the tubular portion of the clamping element to force it into closeclamping engagement with the enclosed legs and end portion of theconductor I as shown to the best advantage in Fig. 5. In order toprovide additional assurance that the clamping element I I will besecurely fixed to the eye I0 portions of the tubular portion of saidclamping element are forced into the material of the legs Iflb of saideye III, by means of punching operations, for instance, as indicated bythe reference character I2 and as shown to good advantage in Fig. 5. Asshown in Fig. 5 the portion of the conductor I located within thetubular portion of the clamping means II is flattened and otherwisedistorted by the clamping pressure to which the tubular portion of theclamping element II is subjected so that it conforms to the shape of apart of the space within the tubular portion of the clamping element IIand thus is securely clamped within the clamping element. Also theextreme outer end portion Ia of the conductor I extends outwardly beyondthe tubular portion of the clamping element II, and as this portion. Iatends to spread because of the clamping pressure applied to theconductor portion located within the tubular portion of the clampingelement I I the gripping action between the conductor I and the clampingelement I I is increased.

At the opposite, or lower, end of the fuse link L an eye I3 is attachedto the conductor 2 in the same manner in which the eye I0 is attached tothe conductor I as has been described above. In other words the eye IIis formed of relatively stifi. wire, or other suitable' material, andincludes substantially parallel leg portions which are extended into thetubular portion Ila of a clamping element II which is similar to theclamping element II associated with the eye II.- Also the end portion ofthe conductor 2 is extended into the tubular portion of the clampingelement I4 and clamping pressure is applied to the tubular portion ofthe clamping element II to secure the eye II to the conductor 2. Asshown in Fig. 1 the portion of the eye II which is extended beyond theclamping element I4 is substantially circular in shape, but obviously,if

desired, this portion of the eye I! may have the same shape as thecorresponding portion of t eye. I0.

In applying the improved fuse link L disclosed herein to a switch of thegeneral type illustrated in Fig. 1, a switch stick S is employed and thefinger So of this switch stick is introduced into the extension lie ofthe eye I0 of the fuse link as shown in Fig. 1. The fuse link L is thenelevated to the location of the switch with the aid of the switch stick,and a portion of the conductor 2 which is located adjacent to theclamping element I I is introduced between one of the rearwardly bentportions J of the lower contact H and an adjacent portion of said lowercontact which is located inwardly of said rearwardly bent portion J, thefuse link L being pulled outwardly relative to the switch to draw saidportion of the conductor 2 deep in the fuse link-engaging portionprovided by said rearwardly bent portion J of the lower contact and saidadiacent portion of said lower contact so that the conductor 2 will besecurely gripped by said fuse link-engaging portion of thelower contact.The fuse link. L is then elevated with the aid of the switch stick S,carrying with it the outer portion of the lower contact H, and a portionof the conductor I located adjacent to the clampins element II is drawnforwardly into one of the fuse link-engagin portions provided by one ofthe rearwardly bent portions" RI of the upper contact and an adjacentportion of said upper contact located inwardly of said rearwardly bentportion J. The finger of the switch stick is then withdrawn from theextension lllc of the eye In and the switch A is in a fused conditionwith the fuse link held in tension because of the tendency of the outerportion of the lower, resilient contact to move downwardly. When, in theuse of a switch so fused, afault occurs on the line with which theswitch is associated, the outer portion of the lower contact of theswitch is freed from the restraint normally imposed on it by theunruptured fuse link because the excessive current passing through thefuse link due to the occurrence of the fault, melts the fusible elementand the strain wire. This permits the outer portion of the lower contactof the switch to snap downwardly and pull the separated portionsof thefuse link apart and thereby extinguish the electrical are within thetubular structure of the fuse link, the gas produced within the innertube of the tubular structure of the fuse link by the presence of theelectrical arc aiding in such extinguishment of the arc.

It is obvious that because of the shape of the eye in at the upper endof the fuse'link L there is very little likelihood that this eye willunintentionally slip of! of the finger Sa of the switch stick S when thefuse link is being elevated with the aid-of the switch stick against thedownward pull of the lower contact H of the switch A to apply the upperportion of the fuse link to the upper contact G of the switch. This isso because the extension lie of said eye I0 closely embraces the fingerSo of the switch 8 throughout the greater portion of its circumferenceand therefore the enlarged head Sb at the outer end of the switch stickfinger will prevent the eye tion, means for maintaining said tube inposition in embracing relation with respect to said fusible portion, aneye attached to one of said terminal conductors and adapted to beengaged-by a headed finger of a fuse stick when the fuse link is beingintroduced into place for use, said eye having an inner portion ofsuillcient diameter to permit the head portion of the fuse stick fingerto pass laterally therethrough and said eye having an outer portionwhich is adapted to closely embrace the fuse stick finger and which isof such reduced width relative to the diameter of the inner eye portionthatthe head portion of the fuse stick finger may. not pass laterallytherefrom,

. and means for securing said eye to the terminal conductor with whichit is associated.

2. A unitary fuse link comprising terminal conductors, a fusible portionin electrical connection with said terminal conductors, a tube formed ofelectrical insulating material arranged in emfuse stick finger and whichis bracing relation with respect to said fusible portion, means formaintaining said tube in embracing relation with respect to said fusibleportion, an eye attached to one of said terminal conductors and adaptedto be engaged by a headed finger of a fuse stick when the fuse link isbeing introduced into place for use, said eye having an inner portion ofsuflicien't diameter to permit the head portion of the fuse stick fingerto pass laterally therethrough, an outer portion that it adapted toclosely embrace the of such reduced width relative to the diameter ofthe inner eye portion that the head portion of the fuse stick finger maynot pass laterally therefrom, and an extension projected from said innereye portion, and clamping means for attaching said extension of the eyeto the terminal conductor with S which the eye is associated.

- extension lllc from sliding from the switch stick I 3. A unitary fuselink comprising terminal conductors, a fusible portion in electricalconnection with said terminal conductors, a tube formed of electricalinsulating material arranged in embracing relation with respect to saidfusible portion, means for maintaining said tube in embracing relationwith respect to said fusible portion, an eye attached to one of saidterminal conductors and adapted to be engaged by a headed finger of afuse stick when the fuse link is being introduced into place for use,said eye having an inner portion of sufficient diameter to permit thehead portion of the fuse stick flnser to'pass laterally therethrough, anouter portion that is adapted to closely embrace the fuse stick fingerand which is of such reduced width relative to thediameter of the innereye portion that the head portion of the fuse stick finger may not passlaterally therefrom and substantially parallel extensions projected fromsaid inner eye portion, and clamping means which embraces said parallelextensions of the eye and a portion of the terminal conductor with whichthe eye is associated for securing the eye to the terminal conductorwith which it is associated.

(.LHART-IEBAIZ'IN'FOXv

